Bent Spike-rush Southern Mountain population
Scientific Name: Eleocharis geniculata
Taxonomy Group: Vascular Plants
Range: British Columbia
Last COSEWIC Assessment: April 2009
Last COSEWIC Designation: Endangered
SARA Status: Schedule 1, Endangered
Image of Bent Spike-rush
Bent Spike-rush is a small annual, generally 2 to 15 cm tall, but can sometimes reach heights of 20 cm. This tufted plant is composed of numerous slender stalks. Stalks are usually terminated by a single spikelet, approximately 3 to 7 mm long, containing small flowers. This spikelet is composed of hermaphrodite flowers, having both male and female organs, and 1.5 to 2 mm long scales. The plant produces smooth, shiny black dry fruitlets called achenes. Each achene is tipped with a flat and fairly wide tubercle. The black achenes distinguish this species from most other tufted Canadian species of Spike-rush. In British Columbia, Bent Spike-rush can be confused with Purple Spike-rush, which is also a small tufted plant that has black achenes at maturity. However, achenes of Bent Spike-rush are typically twice as long, its tubercles are always bigger and flatter, and its spikelets are more blunt than those of Purple Spike-rush.
Distribution and Population
Bent Spike-rush, which occurs in all tropical areas around the world, is fairly widespread in the southern parts of North America. In Canada, it has been reported from one location in British Columbia, an Osoyoos Indian Band property on the east shore of Osoyoos Lake, and from three sites in southwestern Ontario along the northern shore of Lake Erie. These occurrences are divided into two distinct populations: the Southern Mountain population, in British Columbia, and the Great Lakes Plains population, in Ontario. In 2007, the Southern Mountain population was estimated at more than 10 000 mature individuals. There are insufficient data to assess the trends of this population. The species’ range in the province appears not to have changed over the short term, but has probably declined historically. In recent years, many environments suitable for the species have been searched, but no plants were found.
Bent Spike-rush is a wetland species found on sand or soil along the edges of ponds and lakes; along canal, river and creek banks; in dunes or other types of depressions; in lagoons and mud flats; and in irrigation ditches and rice fields. In Canada, this species is restricted to open sandy or muddy soils that are free from competition from taller and more aggressive plants. In British Columbia, the Southern Mountain population of Bent Spike-rush has been found on soil at the edges of ephemeral ponds. These wetlands are flooded throughout much of the year and usually dry during the spring and summer, but sometimes flood again in late summer or early autumn as a result of lake level changes or a late discharge of groundwater from the mountains to the east. Numerous, mostly low-growing plant species are associated with the habitat of the Bent Spike-Rush Southern Mountain population. In British Columbia, these species include a significant number of endangered plants, including Scarlet Ammannia and Short-rayed Alkali Aster as well as, occasionally, Toothcup and Small-flowered Lipocarpha. In British Columbia, the habitat of the Southern Mountain population appears stable.
When conditions are favourable, Bent Spike-rush grows each year from overwintering achenes. Plants grow into early autumn and produce flowers and achenes, then wither and die during the onset of winter. However, not all achenes that are produced germinate the following year. Some remain dormant in the soil, sometimes for many years. Bent Spike-rush depends on this seedbank to maintain the population over the long term, even through years of adverse growing conditions when few or no plants are produced. Annual plants often have wide fluctuations in plant size and numbers and in the numbers of flowers and achenes produced from year to year. In Bent Spike-rush, reproduction is entirely by seed, as there are no means of asexual reproduction in this species. Achenes probably fall close to the plant, but may be moved around the habitat by water flow or animals.
In addition to its restriction to a rather specific and geographically limited habitat, Bent Spike-rush is threatened in Canada by several factors, including degradation of this habitat. In British Columbia, even though the small Southern Mountain population is protected by a fence, trampling and soil disturbance by cattle and horses occasionally occurs. However, before this site was fenced, livestock grazed across the site for many decades and did not extirpate the populations of Bent Spike-rush or other rare species that are restricted to the site. Human-related disturbances pose another threat to this population. The shoreline to the south and east is frequently used by boaters and swimmers. Invasive species, including many grasses, may pose a threat, in particular Reed Canary Grass. Weed removal efforts have targeted areas where rare species have been found. Finally, artificial management of the water levels of Osoyoos Lake by the Zosel Dam in Oroville in the United States may pose a potential threat to the small Bent Spike-rush population. Lake levels have been managed for at least the last 20 years and the species remains at the site; however, in the last few years, increased erosion by wave action has been observed along the shorelines of several portions of the shore of Osoyoos Lake.
Federal ProtectionThe Bent Spike-rush, Southern Mountain population, is protected under the federal Species at Risk Act (SARA). More information about SARA, including how it protects individual species, is available in the Species at Risk Act: A Guide.
The Southern Mountain population of Bent Spike-rush is not protected by any provincial legislation in British Columbia. However, it is protected within a fenced area by the Osoyoos Indian Band.
Provincial and Territorial Protection
PLEASE NOTE: Not all COSEWIC reports are currently available on the SARA Public Registry. Most of the reports not yet available are status reports for species assessed by COSEWIC prior to May 2002. Other COSEWIC reports not yet available may include those species assessed as Extinct, Data Deficient or Not at Risk. In the meantime, they are available on request from the COSEWIC Secretariat.
8 record(s) found.
- COSEWIC Status Reports (1 record(s) found.)
- COSEWIC Assessments (1 record(s) found.)
- Response Statements (1 record(s) found.)
- Orders (2 record(s) found.)
- COSEWIC Annual Reports (1 record(s) found.)
- Consultation Documents (1 record(s) found.)
- Recovery Document Posting Plans (1 record(s) found.)
COSEWIC Status Reports
COSEWIC Annual Reports
COSEWIC Annual Report - 2009 (2009)2009 Annual Report to the The Minister of the Environment and the Canadian Endangered Species Conservation Council (CESCC) from the Committee on the Status of Endangered Wildlife in Canada.
Recovery Document Posting Plans
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